In a 3rd Generation Partnership Project (3GPP) evolved universal terrestrial radio access (E-UTRA) communication system, during transmission of a physical data channel for a user equipment (UE), the UE needs to be notified through scheduling assignment instructions of the system. The scheduling assignment instructions are usually borne by a physical downlink control channel (PDCCH), and the scheduling assignment instruction is, for example, a downlink scheduling grant (DL_grant) corresponding to a physical downlink shared channel (PDSCH) and an uplink scheduling grant (UL_grant) corresponding to a physical uplink shared channel (PUSCH).
In a long-term evolution (LTE) frequency division duplex (FDD) system, data transmission can only be performed on a pair of uplink and downlink component carriers at a UE side and a network side, the PDCCH includes two types of scheduling indication signaling: DL_grant and UL_grant, specifically used for indicating scheduling of the downlink or uplink physical data channel resource corresponding to the UE on the component carrier pair. However, after the carrier aggregation technology is introduced into the LTE-Advanced system, at the UE side and the network side, data can be transmitted on a plurality of component carriers or component carrier pairs at the same time, and the scheduling signaling of the data channel corresponding to each component carrier is independently encoded, so that the resource scheduling signaling on each component carrier needs a PDCCH.
In a carrier aggregation system, a PDCCH corresponding to a UE may be transmitted on each component carrier, so as to schedule transmission of a PDSCH of the UE on the component carrier or a PUSCH corresponding to the component carrier. Alternatively, the PDCCH of the UE may be transmitted on one or more component carriers. At this time, the PDCCH can not only indicate transmission of a data channel on a downlink component carrier on which the PDCCH is and a corresponding uplink component carrier, but also may further indicate transmission of a data channel on a downlink component carrier different from that of the PDCCH or a component carrier that is not correspondingly uplink paired.
For a UE, when PDCCHs corresponding to multiple component carriers are transmitted on a component carrier or a few component carriers, as a search space corresponding to a control channel has a limited size, the probability of collisions between the control channels is high, which may result in that a part of the PDCCHs of the UE cannot be scheduled, so that a part of the data of the UE cannot be transmitted, and the throughput of the UE is reduced.